arXiv subjects

Zhenglu Duan

Publications and source records attributed to Zhenglu Duan.

12 recordsLinked to original sources

arXiv2024

Simultaneous vibrational resonance in the amplitude and phase quadratures of an optical field based on Kerr nonlinearity

Vibrational resonance (VR) is a nonlinear phenomenon in which the system response to a weak signal can be resonantly enhanced by applying a high-frequency modulation signal with an appropriate amplitude. The majority of VR research has focused on amplifying the amplitude or intensity of the system response to a weak signal, whereas the study of the phase information of system responses in VR remains limited. Here, we investigate the VR phenomena in both amplitude and phase quadratures of an optical field in a Kerr nonlinear cavity driven by a near-resonant weak signal and a far-detuned modulation signal. Analytical and numerical results demonstrated that the resonant enhancement in the amplitude and phase quadratures of the system response to a weak signal simultaneously occurs as the amplitude of the modulation signal is varied. There is a linear relation between the amplitude and frequency of the modulation signal for achieving an optimal VR effect. Furthermore, we generalized our study to investigate the quadrature at an arbitrary phase and determined that the VR enhancement sensitively depends on the phase. Our findings not only broaden the scope of VR research by incorporating phase information but also introduces an approach for amplifying an optical field by manipulating another optical field.

physics.optics↗

arXiv2020

Antibunched photon-pair source based on photon blockade effect in a nondegenerate optical parametric oscillator

Nonclassical light sources, such as correlated photon-pairs, play an important role in quantum optics and quantum information processing systems. This study proposes a process to generate antibunched photon-pairs in a nondegenerate optical parametric oscillator. It is found that when the parameters of the system satisfy certain conditions, the generated photons in subharmonic modes exhibit a strong antibunching behavior and are strongly correlated with one another. In particular, the average photon-pair number is resonantly enhanced. It is also observed that the conventional photon blockade contributes to this phenomenon. In addition, it is interesting to note that fundamental mode photons can blockade the subharmonic mode photons. We refer to this phenomenon as a heterogeneous photon blockade.

quant-ph↗

arXiv2019

Photon blockade in a bi-mode nonlinear nano-cavity embedded with a quantum-dot

We study the interaction between a quantum-dot and a bi-mode micro/nano-optical cavity composed of second-order nonlinear materials. Compared with the Jaynes-Cummings (J-C) model, except for a coherent weak driving field, a strong pump light illuminates the two-mode optical cavity. Analytical results indicate that the model exhibits abundant non-classical optical phenomena, such as conventional photon blockade induced by the nonlinear interaction between polaritons. It constitutes unconventional photon blockade induced by quantum interference due to parametric driving. We compare the photon statistical properties and average photon number of the proposed model, J-C model, and double-mode driven optical cavity under the same parameters and the proposed model can obtain stronger antibunching photons and higher average photon number.

quant-ph↗

arXiv2019

Conventional and unconventional photon blockade effects in an atom-cavity system

A two-level system interacting with a cavity field is an important model for investigating the photon blockade (PB) effect. Most work on this topic has been based on the assumption that the atomic transition frequency is resonant with the fundamental mode frequency of the cavity. We relax this constraint and reexamine PB in a more general atom--cavity system with arbitrary atomic and cavity detunings from a driving field. The results show that when the signs of the atomic and cavity detunings are the same, PB occurs only in the strong-coupling regime, but for opposite signs of the atomic and cavity detunings, strong photon antibunching is observed in both the weak- and strong-coupling regimes and a better PB effect is achieved compared with the case when the signs are the same. More interestingly, we find that this PB arises from quantum interference for both weak and strong nonlinearities. These results deepen our understanding of the underlying mechanism of PB and may be help in the construction of single-photon sources with higher purity and better flexibility using atom--cavity systems.

quant-ph↗

arXiv2018

Pulse-regulated single-photon generation via quantum interference in a $χ^{(2)}$ nonlinear nanocavity

A scalable on-chip single-photon source at telecommunications wavelengths is an essential component of quantum communication networks. In this work, we numerically construct a pulse-regulated single-photon source based on an optical parametric amplifier in a nanocavity. Under the condition of pulsed excitation, we study the photon statistics of the source using the Monte Carlo wave-function method. The results show that there exits an optimum excitation pulse width for generating high-purity single photons, while the source brightness increases monotonically with increasing excitation pulse width. More importantly, our system can be operated resonantly and we show that in this case the oscillations in $g^{(2)}(0)$ is completely suppressed.

quant-ph↗

arXiv2017

Phonon antibunching effect in coupled nonlinear micro/nanomechanical resonator at finite temperature

In this study, we investigate the phonon antibunching effect in a coupled nonlinear micro/nanoelectromechanical system (MEMS/NEMS) resonator at a finite temperature. In the weak driving limit, the optimal condition for phonon antibunching is given by solving the stationary Liouville-von Neumann master equation. We show that at low temperature, the phonon antibunching effect occurs in the regime of weak nonlinearity and mechanical coupling, which is confirmed by analytical and numerical solutions. We also find that thermal noise can degrade or even destroy the antibunching effect for different mechanical coupling strengths. Furthermore, a transition from strong antibunching to bunching for phonon correlation has been observed in the temperature domain. Finally, we find that a suitably strong driving in the finite-temperature case would help to preserve an optimal phonon correlation against thermal noise.

quant-ph↗

arXiv2015

Induced transparency in optomechanically coupled resonators

In this work we theoretically investigate a hybrid system of two optomechanically coupled resonators, which exhibits induced transparency. This is realized by coupling an optical ring resonator to a toroid. In the semiclassical analyses, the system displays bistabilities, isolated branches (isolas) and self-sustained oscillation dynamics. Furthermore, we find that the induced transparency transparency window sensitively relies on the mechanical motion. Based on this fact, we show that the described system can be used as a weak force detector and the optimal sensitivity can beat the standard quantum limit without using feedback control or squeezing under available experimental conditions.

quant-ph↗

arXiv2015

The focusing effect of cold atomic cloud with a red-detuned Gaussian beam

We have demonstrated an atom-optical lens, with the advantage of a small scale and flexible adjustment of the parameters, realized by a far red-detuned Gaussian laser beam perpendicular to the propagation direction of the cold atomic cloud. The one-dimensional transverse focusing effect of cold atomic clouds at the temperature order of 1 $μ$K freely falling through the atom-optical lens on the micron scale have been studied theoretically and then verified experimentally. It is found that theory and experiment are in good agreement.

quant-ph↗

arXiv2014

Goos-Hanchen-like shift of three-level matter wave incident on Raman beams

When a three-level atomic wavepacket is obliquely incident on a "edium slab" consisting of two far-detuned laser beams, there exists lateral shift between reflection and incident points at the surface of a "medium slab", analogous to optical Goos-Hanchen effect. We evaluate lateral shifts for reflected and transmitted waves via expansion of reflection and transmission coefficients, in contrast to the stationary phase method. Results show that lateral shifts can be either positive or negative dependent on the incident angle and the atomic internal state. Interestingly, a giant lateral shift of transmitted wave with high transmission probability is observed, which is helpful to observe such lateral shifts experimentally. Different from the two-level atomic wave case, we find that quantum interference between different atomic states plays crucial role on the transmission intensity and corresponding lateral shifts.

quant-ph↗

arXiv2012

Slowing light with a coupled optomechanical crystal array

We study the propagation of light in a resonator optical waveguide consisting of evanescently coupled optomechanical crystal array. In the strong driving limit, the Hamiltonian of system can be linearized and diagonalized. In this case we obtain the polaritons, which is formed by the interaction of photons and the collective excitation of mechanical resonators. By analyzing the dispersion relations of polaritons, we find that the band structure can be controlled by changing the related parameters. It has been suggested an engineerable band structure can be used to slow and stop light pulses.

quant-ph↗

arXiv2010

Quantum tunneling time of a Bose-Einstein condensate traversing through a laser-induced potential barrier

We theoretically study the effect of atomic nonlinearity on the tunneling time in the case of an atomic Bose-Einstein condensate (BEC) traversing the laser-induced potential barrier. The atomic nonlinearity is controlled to appear only in the region of the barrier by employing the Feshbach resonance technique to tune interatomic interaction in the tunneling process. Numerical simulation shows that the atomic nonlinear effect dramatically changes the tunneling behavior of the BEC matter wave packet, and results in the violation of Hartman effect and the occurrence of negative tunneling time.

quant-ph↗

arXiv2008

Goos-Hänchen-Like Shifts in Atom Optics

We consider the propagation of a matter wavepacket of two-level atoms through a square potential created by a super-Gaussian laser beam. We explore the matter wave analog of Goos-Hänchen shift within the framework of atom optics where the roles of atom and light is exchanged with respect to conventional optics. Using a vector theory, where atoms are treated as particles possessing two internal spin components, we show that not only large negative but also large positive Goos-Hänchen shifts can occur in the reflected atomic beam.

quant-ph↗